An estimated 250 million people worldwide are infected by pathogenic microorganisms per annum, of which 20 million cases are fatal. Rapid methods of detecting pathogenic infections in humans or the presence of pathogenic agents in water may ensure early diagnosis or prevention of infection, to ultimately reduce the number of fatalities.
A pathogenic infection is caused by a pathogen or infecting agent such as a microorganism, virus, fungus, prion or protozoan and it may cause disease in a host. The immune system of the host launches an immune response when it detects a pathogenic infection, and produces antibodies that recognize a unique part of the foreign target, called an antigen. Antibodies have complementary determining regions that vary so as to be specific for a particular epitope on an antigen, allowing these structures to associate with one another. Antibodies, and their bio recognition capabilities are used extensively as diagnostic tools in a wide variety of analyses. A diagnosis of infection is possible, if it can be determined that a biological sample derived from a subject contains antibodies that selectively associate with a known antigen.
Standard in vitro antibody detection methods such as enzyme-linked immunosorbent assays, magnetic immunoassays, immunoprecipitation, radial immunodiffusion and Western blotting are relatively time consuming techniques and require a skilled person to perform them. Moreover, in a laboratory setting, these methods are more likely to result in diagnostic errors due to human error and the possibility of cross-contamination of samples. Many of the standard methods are qualitative and do not readily allow for the quantification of the amount of antibodies present in a sample.
There thus remains a need for a rapid method of selectively detecting biomolecules, specifically antigens or antibodies linked to pathogenic infection, directly in a subject or within a sample of body fluid obtained from a subject. There also remains a need for the rapid and selective detection of antigens in water samples to determine if the water is contaminated with microorganisms or other pathogenic agents.